The Hair Growth Cycle
It should be explained that in most mammals, hair does not grow continuously, but undergoes a cycle of activity involving alternate periods of growth and rest. The hair growth cycle can be divided into three main stages, namely:
(i) the growth phase known as anagen, during which the hair follicle penetrates deep into the dermis with the cells of the bulb dividing rapidly and differentiating to form the hair, PA0 (ii) the transitional stage known as catagen, which is heralded by the cessation of mitosis, and during which the follicle regresses upwards through the dermis and hair growth ceases, PA0 (iii) the resting stage known as telogen, in which the regressed follicle contains a small secondary germ with an underlying ball of tightly packed dermal papilla cells. PA0 (i) a chemical activator of protein kinase C enzymes chosen from diacylglycerols having the structure (1): ##STR3## where X' is the same or different, and is represented by the grouping: ##STR4## where x is 0, or an integer of from 1 to 28, and y is 0, or an integer of from 1 to 5; PA0 the OX groups being of either stereochemical configuration with respect to the carbon backbone of the glycerol molecule, and the double bonds being of either cis or trans configuration; and PA0 (ii) a cosmetically acceptable vehicle for the chemical activator; PA0 the OX groups being of either stereochemical configuration with respect to the carbon backbone of the glycerol molecule, and the double bonds being of either cis or trans configuration. PA0 1,2-Dibutanoyl-rac-glycerol PA0 1,2-Dihexanoyl-sn-glycerol PA0 1,2-Dioctanoyl-rac-glycerol PA0 1,2-Dioctanoyl-sn-glycerol PA0 1,2-Didecanoyl-rac-glycerol PA0 1-Oleoyl-2-acetyl-rac-glycerol PA0 1-Oleoyl-2-acetyl-sn-glycerol PA0 1-Stearoyl-2-arachidonoyl-sn-glycerol PA0 1,2-Distearoyl-rac-glycerol PA0 1,2-Dipentadecanoyl-sn-glycerol PA0 1,2-Dipentadecanoyl-rac-glycerol PA0 1,2-Dipalmitoyl-rac-glycerol PA0 1,2-Dipalmitoyl-sn-glycerol PA0 1,2-Diseptadecanoyl-rac-glycerol PA0 1,2-Dioleoyl-sn-glycerol PA0 1,2-Dioleoyl-rac-glycerol PA0 1,2-Diarachidonoyl-sn-glycerol PA0 1,2-Dieicosanoyl-sn-glycerol PA0 1,2-Didoeicosanoyl-rac--glycerol, and PA0 1,2-Dioctaeicosanoyl-sn-glycerol. PA0 Benzalkonium chloride PA0 Benzethonium chloride PA0 Phenol PA0 Estradiol PA0 Diphenhydramine hydrochloride PA0 Chlorpheniramine maleate PA0 Chlorophyllin derivatives PA0 Cholesterol PA0 Salicylic acid PA0 Cystine PA0 Red pepper tincture PA0 Benzyl nicotinate PA0 dl-Menthol PA0 Peppermint oil PA0 Calcium pantothenate PA0 Panthenol PA0 Castor oil PA0 Hinokitiol PA0 Prednisolone PA0 Resorcinol PA0 Retinoids, or pharmaceutically acceptable esters, ethers or salts thereof. PA0 (i) .delta.-1,4 esterified disaccharides described by Choay S.A. in EP-A-O 064 012, having the structure (50): ##STR7## where Z represents a functional nitrogen group, such as an azide or a group having the structure --NHB, in which B represents --H or a functional group such as acetyl or sulphate as a salt with an organic or mineral cation; PA0 (ii) esterified oligosaccharides as described by Unilever in EP-A-O 211 610, including at least one esterified disaccharide unit consisting of a uronic acid residue having the structure (51): ##STR8## and a hexosamine residue having the structure (52): ##STR9## where R' is --H, C.sub.3 to C.sub.10 alkyl or ##STR10## R" is --H, C.sub.1 to C.sub.4 alkyl, --CO(CH.sub.2).sub.m CH.sub.3, --SO.sub.3 M', PA0 (iii) Minoxidil and its derivatives, PA0 (iv) Minoxidil glucuronides, PA0 (v) Minoxidil sulphates, PA0 (vi) Direct proteoglycanase inhibitors, such as 1,10-phenanthroline. PA0 (vii) Glycosaminoglycanase inhibitors, such as aldonolactones and esterified aldonolactones having the structure (53): ##STR11## where A.sup.1 and A.sup.6 are ##STR12## B is OD" or a lactone linkage to position 1 or 6, or --NHCOCH.sub.3 and where D is --H or C.sub.2 to C.sub.8 alkyl, PA0 L-Galactono-1,4-lactone PA0 L-Arabino-1,5-lactone PA0 D-Fucono-1,5-lactone PA0 D-Glucaro-1,4-lactone PA0 D-Glucurono-6,3-lactone PA0 Galactaric acid lactone PA0 2-Acetamido-2-deoxygluconolactone PA0 2-Acetamido-2-deoxygalactono-lactone PA0 D-Glucaro-1,4:6,3-dilactone PA0 L-Idaro-1,4-lactone PA0 2,3,5-Tri-0-acetyl-D-glucaro-1,4-lactone PA0 2,5-Di-0-acetyl-D-glucaro-1,4:6,3-dilactone PA0 (viii)Glycosaminoglycanase inhibitors, such as monosaccharides and esterified monosaccharides having the structure (54): ##STR13## where A is --OR or --NHCOCH.sub.3 PA0 N-Acetylglucosamine PA0 N-Acetylgalactosamine PA0 D-Galactosamine PA0 D-Glucosamine-3-sulphate PA0 N-Acetylmannosamine PA0 (ix) glycosaminoglycan chain cellular uptake inhibitors such as, hexuronic acid and esters thereof which may be represented by the generic structure (55): ##STR14## where G is --H, --SO.sub.3 M", C.sub.2 (i.e. acetyl) to C.sub.4 acyl; PA0 (x) Chemical inhibitors of glycosidase activity chosen from lactams having the structure (56): ##STR15## where A.sup.1 and A.sup.6 are ##STR16## A.sup.1 and A.sup.6 being the same or different, and at least one of which being the group: ##STR17## in a lactam ring; and where Q is --OT', --NHT' or a lactam linkage to A.sup.1 to A.sup.6 ; PA0 D-glucaro-1,5-lactam PA0 L-Galactono-1,4-lactam, PA0 L-Arabino-1,5-lactam, PA0 D-Fucono-1,5-lactam, PA0 D-Glucaro-1,4-lactam, PA0 D-Glucurono-6,3-lactam, PA0 1,2,5-tri-O-acetyl-D-glucurono-6,3-lactam PA0 2-Acetamido-2-deoxygluconolactam, PA0 2-Acetamido-2-deoxygalactonolactam, PA0 D-Glucaro-1,4:6,3-dilacteun, PA0 L-Idaro-1,4-lactam, PA0 2,3,5-Tri-O-acetyl-D-glucaro-4-lactam, PA0 2,5-Di-O-acetyl-D-Glucaro-1,4:6,3-dilactam, PA0 D-glucaro-1,5-lactam ethyl ester; PA0 2-methyl propan-2-ol PA0 Propan-2-ol PA0 Ethyl-2-hydroxypropanoate PA0 Hexan-2,5-diol PA0 POE(2) ethyl ether PA0 Di(2-hydroxypropyl) ether PA0 Pentan-2,4-diol PA0 Acetone PA0 POE(2) methyl ether PA0 2-hydroxypropionic acid PA0 2-hydroxyoctanoic acid PA0 Propan-1-ol PA0 1,4 Dioxane PA0 Tetrahydrofuran PA0 Butan-1,4-diol PA0 Propylene glycol dipelargonate PA0 Polyoxypropylene 15 stearyl ether PA0 Octyl alcohol PA0 POE ester of oleyl alcohol PA0 Oleyl alcohol PA0 Lauryl alcohol PA0 Dioctyl adipate PA0 Dicapryl adipate PA0 Diisopropyl adipate PA0 Diisopropyl sebacate PA0 Dibutyl sebacate PA0 Diethyl sebacate PA0 Dimethyl sebacate PA0 Dioctyl sebacate PA0 Dibutyl suberate PA0 Dioctyl azelate PA0 Dibenzyl sebacate PA0 Dibutyl phthalate PA0 Dibutyl azelate PA0 Ethyl myristate PA0 Dimethyl azelate PA0 Butyl myristate PA0 Dibutyl succinate PA0 Didecyl phthalate PA0 Decyl oleate PA0 Ethyl caproate PA0 Ethyl salicylate PA0 Isopropyl palmitate PA0 Ethyl laurate PA0 2-ethyl-hexyl pelargonate PA0 Isopropyl isostearate PA0 Butyl laurate PA0 Benzyl benzoate PA0 Butyl benzoate PA0 Hexyl laurate PA0 Ethyl caprate PA0 Ethyl caprylate PA0 Butyl stearate PA0 Benzyl salicylate PA0 2-hydroxypropanoic acid PA0 2-hyroxyoctanoic acid, PA0 pyroglutamic acid methyl ester PA0 pyroglutamic acid ethyl ester PA0 pyroglutamic acid n-propyl ester PA0 pyroglutamic acid n-butyl ester PA0 pyroglutamic acid n-heptyl ester PA0 pvroglutamic acid n-octal ester PA0 pyroglutamic acid n-nonyl ester PA0 pyroglutamic acid n-decyl ester PA0 pyroglutamic acid n-undecyl ester PA0 pyroglutamic acid n-dodecyl ester PA0 pyroglutamic acid n-tridecyl ester PA0 pyroglutamic acid n-tetradcyl ester PA0 pyroglutamic acid n-hexadecyl ester PA0 pyroglutamic acid n-octadecyl ester PA0 pyroglutamic acid n-eicosyl ester PA0 pyroglutamic acid iso-propyl ester PA0 pyroglutamic acid 2-methylhexyl ester PA0 pyroglutamic acid 2-ethylhexyl ester PA0 pyroglutamic acid 3,7-dimethyloctyl ester PA0 pyroglutamic acid 2-hexyldecyl ester PA0 pyroglutamic acid 2-octyldodecyl ester PA0 pyroglutamic acid 2,4,4-trimetyl-1-pentane ester PA0 pyroglutamic acid methyloctyl ester PA0 methyl PA0 ethyl PA0 propyl PA0 iso-propyl PA0 butyl PA0 iso-butyl PA0 n-valeryl PA0 iso-valeryl PA0 n-caproyl PA0 n-heptyl PA0 n-caprylyl PA0 n-capryl PA0 lauryl PA0 myristyl PA0 palmityl PA0 stearyl, and PA0 arachidyl. PA0 linoleyl PA0 linolenyl PA0 .delta.-linolenyl PA0 arachidonyl, and PA0 columbinyl. PA0 hydroxymethyl PA0 2-hydroxyethyl PA0 2-hydroxy-n-propyl PA0 3-hydroxy-n-propyl PA0 2-hydroxy-n-butyl PA0 3-hydroxy-n-butyl PA0 4-hydroxy-n-butyl PA0 5-hydroxy-n-valeryl PA0 6-hydroxy-n-caproyl PA0 2,3-dihydroxy-n-propyl PA0 2,3-dihydroxy-n-buty PA0 12-hydroxystearyl. PA0 2-[pyroglutamoyloxy]-propionic acid PA0 methyl -2-[pyroglutamoyloxy]-acetate PA0 ethyl- 2-[pyroglutamoyloxy]-n-propionate PA0 ethyl- 2-[pyroglutamoyloxy]-n-butyrate PA0 ethyl- 2-[pyroglutamoyloxy]-iso-butyrate PA0 ethyl- 2-[pyroglutamoyloxy]-n-valerate PA0 ethyl- 2-[pyroglutamoyloxy]-n-caproate PA0 ethyl- 2-[pyroglutamoyloxy]-n-heptylate PA0 ethyl- 2-[pyroglutamoyloxy]-n-caprylate PA0 ethyl-2-[pyroglutamoyloxy]-n-pelargonate PA0 ethyl-2-[pyroglutamoyloxy]-3-hydroxybutyrate PA0 iso-propyl-2-[pyroglutamoyloxy]-n-propionate PA0 iso-propyl-2-[pyroglutamoyloxy]-n-caprylate PA0 n-propyl-2-[pyroglutamoyloxy]-n-propionate PA0 n-propyl-2-[pyroglutamoyloxy]-n-caprylate PA0 stearyl-2-[pyroglutamoyloxy]-n-propionate PA0 12-hydroxystearyl-2-[pyroglutamoyloxy]-n-propionate PA0 stearyl-2-[pyroglutamoyloxy]-n-stearate PA0 palmityl-2-[pyroglutamoyloxy]-n-propionate PA0 linoleyl-2-[pyroglutamoyloxy]-n-propionate PA0 linoleyl-2-[pyroglutamoyloxy]-n-caprylate PA0 lauryl-2-[pyroglutamoyloxy]-n-caprylate PA0 stearyl-2-[pyroglutamoyloxy]-n-caprylate PA0 glyceryl mono(2-[pyroglutamoyloxy]-n-propionate) PA0 glyceryl mono(2-[pyroglutamoyloxy]-n-caprylate), and PA0 glyceryl di(2-[pyroglutamoyloxy]-n-propionate). PA0 Dimethyl sulphoxide PA0 N,N-Dimethyl acetamide PA0 N,N-Dimethyl formamide PA0 2-Pyrrolidone PA0 1-Methyl-2-pyrrolidone PA0 5-Methyl-2-pyrrolidone PA0 1,5-Dimethyl-2-pyrrolidone PA0 1-Ethyl-2-pyrrolidone PA0 Phosphine oxides PA0 Sugar esters PA0 Tetrahydrofurfural alcohol PA0 Urea PA0 Diethyl-m-toluamide, and PA0 1-Dodecylazacyloheptan-2-one PA0 (i) Anionic surface active agents, such as metallic or alkanolamine salts of fatty acids for example sodium laurate and triethanolamine oleate; PA0 (ii) Cationic surface active agents, such as a/nine salts, for example sapamin hydrochloride; PA0 (iii) Amphoteric suface active agents, such as imidazol compounds, for example Miranol; PA0 (iv) Nonionic surface active agents, such as fatty acid alkanolamides, for example oleic ethanolamide;
The initiation of a new anagen phase is revealed by rapid proliferation in the germ, expansion of the dermal papilla and elaboration of basement membrane components. The hair cycle is then repeated many times until, as a consequence of the onset of male pattern baldness, most of the hair follicles spend an increasing proportion of their time in the telogen stage, and the hairs produced become finer, shorter, and less visible; this is known as terminal to yellus transformation.